Persistent Trojan/WRAT AV companies useless

I have a trojan or RAT that keeps fucking (excuse my French) with my
windows 8.1 system. Deletes files, shortcuts, changes settings, makes
executables either disappear or not load-I am no longer getting this 

"file cannot be run on your pc message" tho.

I have run f-prot one, eset online scanner, trend micro and 
KVRT. (KVRT never finished even after 30 hours running and I had to 
nuke the process-no longer a Kaspersky fan)

Long long process times on about 400gb of data across-
 several partitions. After several days an repeated scans lastest scans 

indicate no infections, but the system is still stuffed. Many different 

viruses were quarantined, but the main one was heur.virus.win32.chir.gen
put a ton of .scr files on my drive and their are still some there but
not on critical files I am thinking? 

The only way I can run online without further deterioration
is in safe mode. So I am guessing the trojan is part of some
installed/corrupted OS file I have not been able to locate?

So when I am online without safe mode the fucker(s) who
nuked my system are fucking with me.

The so-call best av programs have not solved the issue.
This is a bootlegged version of win 8.1 (not all of us can
afford to buy software or want to send our CC info online) 
that has worked well for several years when I plugged in a usb and
immediately all the files starting showing .scr extensions. 

What to do? Any HELPFUL advice is gratefully appreciated.
I realize I am not always the most friendly guy online, but
I really would appreciate and remember anyone who gives a good
reply (what goes around..)
Thanks in advance. Purposely cross posted since this is
both a windows system problem and and antivirus problem.

My next step is to wipe the hard drive an install a new OS since
NONE of the AV programs have dealt with the issue and frankly I am
disappointed in these companies. Their "free trial" offerings should
be renamed: we will let you beta test and fix our sloppy work for free.

Also I have been unable to reinstall a fresh copy of paint-net:
"Setup has detected configuration problems and must exit". Has
something to do with permissions but I'm not sure what.